I think it's safe to say that everyone enjoys personally unboxing a brand new item. You've been waiting days for your new package and you can't help but get more and more excited as you uncoil wires and discover pamphlets of welcome messages and instructions you'll never touch again.
But why do so many people make and watch unboxings of items other people have received? Were you really expecting anything more than bag ties and tape and cardboard containments? Probably not. But as PBS Idea Channel's Mike Rugnetta notes, there are probably a few reasons for this.
For one thing, it's a bit of a fetishization of the product/owning that product. Lots of people on the Internet have a shared appreciation for owning a brand new iPhone or are excited to see the first few new Xbox Ones out in the wild. These products are stripped of any glossy after effects that a marketing team would pile on to them, too. If you've ever watched a McDonalds ad and then gone into a physical McDonalds and ordered the same cheeseburger, you're doubtless aware of the power of presentation.
Rugnetta makes a few other pointed observations that are worth thinking about but whatever the motivation may be, the likes of YouTube and other sources have made one thing evident: people sure do like their unboxing videos.